DEVELOPMENT OF CUCUMARIA ECHINATA 1 ayia 
I believe I have been able to throw some light upon the embryo- 
logy of the group. 
The present work was started while in the Zoological Institute 
of the Tokyo Imperial University, but the greater part of it 
was carried on in the biological laboratory of the Fifth High 
School in Kumamoto, and it was completed in November of 
1918. Owing, however, to the pressure of various affairs it could 
not have been published before I had left Kumamoto the next 
summer. The manuscript was then brought with me to London, 
and has been subjected to Professor E. W. MacBride’s 
kind and careful revision. It is my pleasant duty here to express 
my hearty thanks to Professor I. 1jima and Professor $. Goto 
for their kindly supervision, and to various others for their help. 
Further, I extend my gratitude to Mr. K. Yoshioka, Director 
of the Fifth High School, by whose favour I have been able to 
enjoy many facilities to assist me in my studies. Lastly, to 
Professor Mac Bride, to whose courtesy the appearance of 
this paper is entirely due, I beg to tender my deepest indebtedness, 
2. PREviIous StuDIES ON ALLIED Forms. 
So far as the embryology of apodous holothurians and our 
knowledge of typical auriculariae are concerned, the famous 
works of J. Miller, Metschnikoff, Semon, Bury, 
Mortensen, and Clark are unrivalled ; but our knowledge 
of the pedate forms is meagre and, for the most part, fragmentary. 
This meagreness is due, I think, partly to the fact that artificial 
fertilization is very difficult,’ and partly to the shortness of the 
larval stage, the auricularia stage being usually omitted,? so 
that the larva easily escapes the eyes of investigators of the 
1 Clark (7, 1898, p. 58), Mitsukuri (80, 1903, p. 11), and 
Edwards (12, 1909, p. 212) never succeeded, while Selenka’s 
experiment (45, 1876, p. 157) resulted in the malformation. Only one 
case of successful artificial fertilization is recorded by Mortensen in 
Holothuria nigra, though in this case only a small percentage 
of the eggs developed (35, 1913, pp. 17-18). 
* Holothuria tubulosa and H. nigra pass through a typical 
auricularia stage (Selenka, 45; Mortensen, 35). 
